Constant versus dissipating forces in orthodontics: the effect on initial tooth movement and root resorption

Abstracts on this page have been chosen and edited by Dr Trevor Watts

Abstract

Constant forces moved teeth quicker but led to greater root resorption.

Main

Weiland F. Eur J Orthod 2003; 25: 335–342

In 27 patients of mean age 12.5 yrs, 90 premolars scheduled for orthodontic extraction were actively moved buccally (84) or used as controls (6). Test teeth were treated in pairs: on one side a stainless steel wire was used (initially high but rapidly declining force), but on the other, a superelastic arch wire (initially lower force of 1N but constant from 4 to 0.25 mm deflection).

The superelastic wire moved teeth significantly more (3.5 mm) than the stainless steel wire (2.3 mm) and tipped further buccally. On extraction, one small resorption was found on a control tooth root with confocal microscopy, but more were found on test teeth. Mean depth of resorption did not differ between the test groups, but a significantly greater area was affected in the superelastic group.